"Since you used Stripe Subscriptions in the past year, the Stripe Billing Starter plan is included in your current pricing."
Edit: Since my posting this Stripe has clarified that existing customers get the Starter package at no further cost, we we are grandfathered in.
> Since you used Stripe Subscriptions in the past year, the Stripe Billing Starter plan is included in your current pricing.
Which implies you're opted into the Starter Plan with the regular 1+mil fees.
The initial communication left some room for clarity, which really had me confused in the same way as others in this thread. Really outside of the norm for Stripe, who's communication is usually very clear.